Summary of a research project funded by the National Honey Board and conducted
at the University of Nebraska-Lincoln Food Processing Center. Investigator:
M.B. Preston.
This project was designed to formulate a chocolate milk beverage using honey as the sweetener source. The use of honey in milk beverages would provide many advantages to the products such as flavor, color and mouthfeel as well as serve as a high carbohydrate/high energy source. The heavier, thicker mouthfeel desirable in some beverage products could be enhanced by the use of honey. Honey would be a more “consumer friendly” ingredient on the label than other types of body modifiers and would lend a more "natural" and healthful image to a product. The use of honey in a chocolate milk beverage would also produce a product with the flavor appeal children enjoy and an image that parents would find appealing as well.
The objectives of this project were to:
A basic formulation for refrigerated chocolate milk was developed and is given in Table 1. The honey used in the formulation was a light-colored, grade A, clover honey. The cocoa used was a premium cocoa with a fat content of 10-12 %. The milk used was raw milk with a fat content of 3.2%. Additional formulations were developed as addenda to the original project proposal. The base formulation was modified to develop formulations for flavored chocolate milk beverages with adult appeal. Several flavors (hazelnut, macadamia nut, almond and Irish cream) were incorporated into the base formula. The objective was to develop a line of fat-free or low-fat flavored chocolate milks (containing low-fat milk and cocoa) and soluble fiber (Benefiber.) in order to produce a more upscale, adult version of a classic children's beverage. This portion of the project was completed with the development of sample formulations
During the formulation phase, in-house evaluations were conducted. The initial processing procedure for the chocolate milk during the formulation development stage was to combine all ingredients using a hand blender and formulating with pasteurized milk. The mixture was not homogenized at this point therefore separation occurred. However, when the milk was prepared for the storage study and sensory evaluation, the formulation process began with raw milk. The raw milk was mixed with cocoa, liquid honey, carrageenan, sodium chloride and vanilla. The liquid honey was heated prior to adding and mixing with the other ingredients to facilitate blending. The mixture was then homogenized in two stages with a single pass using a Soavi homogenizer. The pressures used for the homogenization process were 2000 psi for the first stage and 500 psi for the second stage. The milk was then pumped through a coil pasteurizer using a Masterflex pump and heated to 170°F for 20 seconds and cooled. The glass jars were filled with the pasteurized product and stored at 40°F for the duration of the shelf-life study.
Shelf-life determination was designed for the refrigerated chocolate milk to evaluate changes in viscosity, sedimentation, color, microbiological load and sensory attributes. The milk beverage was processed and stored for 14 days at refrigerated temperature (40 °F) in glass jars. Samples were evaluated and analyzed in triplicate at days 0, 7 and 14. Sensory analysis was conducted at day 0 and day 7. In addition to the storage study, a commercial (no honey) chocolate milk was analyzed for viscosity, sedimentation, color and sensory analysis and compared to the day 0 sample.
The viscosity of the products was measured using a Brookfield Viscometer, Model LVT, following written instructions provided with the instrument. The setting on the viscometer was at 12 rotations per minute (rpm) utilizing the number two spindle. The viscosities were evaluated using 185.0 grams of sample poured into an eight-ounce glass jar identical to those used to hold the product for the storage study. The analysis was conducted in triplicate for three samples. Viscosity analysis was conducted on days 0, 7 and 14. No changes were found in viscosity between storage dates and viscosity was similar to the commercial product. The results are illustrated in Table 3.
Sedimentation was evaluated at day 0, 7 and 14. The samples were stored in eight-ounce glass containers. Sedimentation of the product was measured using a ruler to record the thickness of the sediment in the bottom of the glass jar. Table 4 provides a summary of the data. Sedimentation was observed on day 0 after homogenization and in samples subsequently analyzed on days 7 and 14. However, if a sample was agitated 24 hours postproduction, the cocoa remained in suspension for the duration of the 14 day study.
The color of the chocolate milk was analyzed at days 0, 7 and 14 using a Minolta Chroma Meter CR-300 programmed for the Hunter Lab Color System (Minolta Corporation, Instrument Systems; Ramsey, NJ). The color was analyzed by measuring 100 ml of chocolate milk into a 250-ml beaker. The beaker was placed on a black surface. The chroma meter was calibrated using a white calibration plate. The Hunter Lab Color system determines the values for the perceived color. Lightness is expressed by "L" values and "a" and "b" values are the chromaticity coordinates. Lightness was expressed as dark to light color with 0 = black and 100 = white. Green to red was expressed by the "a" value, the more positive value represented more red, while the more negative value represented more green color (-80 = green, 100 = red). Blue to yellow was expressed by the Table 5. Color Analysis Results "b" value, a more positive value represented more yellow color in the sample (-80 = blue, 70 = yellow). Refer to Table 5 for the results of the color measurements for all test dates. The color values did not change during storage. The commercial chocolate milk was darker and more green than the experimental treatment; however, the "a" and "b" values were similar.
The products were evaluated for lactic acid bacteria, total plate counts, yeast and molds on day 0. On day 7, the total plate count was replaced with a psychrotrophic bacterial count as the product had been stored under efrigeration and any spoilage which may have occurred would have been caused by psychrotrophic organisms. Results on day very low, therefore total plate count was added at day 14 to compare to the sychrotrophic counts. Yeast and mold analysis was discontinued after day 7. Overall, the microbiological counts were low for the duration of the 14-day storage study (Table 6).
Samples tested were either chocolate milk formulated with honey or chocolate milk that is commercially available. Panelists were asked to evaluate the samples for appearance, texture, flavor, chocolate flavor and overall acceptability using a modified Hedonic scale.
Results (Table 7) showed that no significant differences were found between the two samples. After the initial screening the honey-treated chocolate milk was evaluated over time for acceptability for the same set of attributes. Results (Table 8) showed no loss of acceptability after seven days of refrigerated storage.
Sensory and shelf life research indicated that honey can be used in chocolate milk beverages and yield positive results. Honey also provides a natural image to chocolate milk beverages. The tests determined that:
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